Marriage is honorable among all, and the bed undefiled; but fornicators and adulterers God will judge.
-Hebrews 13:4, NKJV
What if you find out your spouse cheated on you while you were dating or engaged but kept it a secret?
This is damaging on multiple levels:
First, you have the cheating.
Discovering cheating is a real gut punch. It is hard to process that information. The person we thought was safe was truly and utterly unsafe. Our world is upended.
Second, you have all the lies that protected the dirty secret.
How do you rebuild trust after living in a relationship where such vital information was withheld for so long? That is tough.
In fact, this might be the worst part of the whole thing. You are dealing with someone who manipulated for as long as they kept the secret to avoid dealing with consequences.
I believe Scripture allows for divorce in these circumstances as such infidelity falls under the broad category of sexual immorality (see Mt 19:9). It is that serious!
Honestly, I would question what other lies the partner had kept as well. It becomes a way of life when you hold such a secret for a long time.
Such behavior demonstrates a willingness to choose themselves over the difficult work of truthful conversation. That is not good. Plus, that is incompatible to Christian living as we are called to live in the light (see John 3:20-21).